Transfer switch for tapped regulating transformers with radial guide and linkage structure



May 10, 1966 A. BLEIBTREU 3,250,865

TRANSFER SWITCH FOR TAPPED REGULATING TRANSFORMERS WITH RADIAL GUIDE AND LINKAGE STRUCTURE Filed May 22, 1964 4 Sheets-Sheet l [WWW y 10, 1966 A. BLEIBTREU 3,250,865

TRANSFER SWITCH FOR TAPPED REGULA'II TRANSFORMERS WITH RADIAL GUIDE AND LINKAGE RUCTURE Filed May 22, 1964 4 Sheets-Sheet 2.

May 10, 1966 BLEIBTREU 3,250,865

TRANSFER SWITCH FOR TAPPED REGULATING TRANSFORMERS. WITH RADIAL GUIDE AND LINKAGE STRUCTURE Filed May 22, 1964 4 Sheets-Sheet 5 W n/r04 Mum WW M Wm M A y 1966 A. B IBTREU 3,250,865

TRANSFER SWITC OR TA D REGULATING TRANSFORMERS WITH RAD GUIDE AND LINKAGE STRUC E Filed May 22, 1964 Sheets-Sheet 4.

Arm-wrap MIX/(AMA WWW W WW United States Patent 3,250,865 TRANSFER SWITCH FOR TAPPED REGULATING TRANSFORMERS WITH RADIAL GUIDE AND LINKAGE STRUCTURE Alexander Bleibtreu, Regensburg, Germany, assignor to Maschinenfabrik Reinhausen Gehriider Scheuheck K.G., Regensburg, Germany Filed May 22, 1964, Ser. No. 369,475 Claims priority, application Germany, July 18, 1963,

M 57,543 13 Claims. (Cl. 200-11) This invention is concerned with transfer switches for tapped regulating transformers, and more particularly with rotary Jansen type transfer switches. An important feature of Jansen ty-pe transfer switches resides in the fact that the movable contacts thereof are under the control of snap-action operating mechanisms adapted to impart to their movable contacts high switching velocities, particularly high velocities of separation from the fixed contacts thereof.

It is a general object of this invention to provide improved transfer switches of the aforementioned character.

The design of a transfer switch depends largely upon whether it is intended for single-phase application, or polyphase application. Single phase designs of transfer switches are applied in single phase circuits, and also in polyphase circuits whenever it is necessary, or desirable, to use a separate transfer switch for each phase of the polyphase circuit. Such a situation may exist in a three phase circuit including a transformer having tapped deltaconnected phase windings. In polyphase designs of transfer switches the movable contacts !and the fixed contacts of all phases are integrated into a structural unit. Such polyphase designs of transfer switches are particularly applied in three phase circuits including a transformer having tapped Y-connected windings.

This invention is concerned with transfer switches intended for single phase applications, as explained above, i.e., transfer switches comprising movable switching contacts and operating linkages therefor limited to the duty of performing the switching operations pertaining to one single phase. In other words, this invention is not concerned with a transfer switch of the type comprising movable switching contacts and operating linkages therefor adapted to perform the switching operations pertaining to several phases of a polyphase circuit, and wherein the contacts and linkages are integrated into one unitary switch structure.

Jansen type transfer switches are generally operated by motor means or, to be more specific, by loaded springs pre-storing the energy for performing the required'sequence of switching operations, or switching steps, to switch from one tap of a transformer winding to another. These loaded springs determine the intervals of time which occur between successive switching operations, or switching steps, as well as the speed at which cooperating contacts part from each other, and engage with each other.

It is another object of this invention to provide transfer switches for tapped regulating transformers which make it possible to control the relative speeds at which cooperating fixed and movable contacts part and engage independently of the intervals of time which occur between successive switching operations, or switching steps.

The switching capacity or interrupting capacity of a transfer switch for tap-changing regulating transformers depends largely upon the choice of the speed of contact separation. Optimal values of switching capacity or interrupting capacity can only be achieved if it is possible to control the speed of contact separation independently from the interval of time elapsing between successive switching operations, or switching steps.

It is, therefore, another object of this invention to provide transfer switches for tapped regulating transformers adapted to optimize the switching capacity, or interrupting capacity, of the transfer switches by controlling at will the speed of separation of cooperating contacts without affecting the speed at which the successive switching operations, or switching steps, are being performed.

Still another object of the invention is to provide transfer switches for tapped regulating transformers having spring means determining the speed at which successive switching operations are being performed, i.e., determining the intervals of time elapsing between successive switching operations, and having additional spring means determining the speed at which cooperating contacts part and engage.

The foregoing and other general and special objects 7 of the invention and advantages thereof will more clearly 20 appear from the ensuing particular description of the invention, as illustrated in the accompanying drawings wherein:

FIG. 1 is a diagrammatic illustration of the contact structure and the linkage structure of a transfer switch embodying this invention and of its association with a tapped transformer winding and with switch-over resistors, the selector switch normally being associated with such a transfer switch as shown in FIG. 1 having been omitted in FIG. 1;

FIG. 2 is a vertical section of a transfer switch of the kind diagrammatically illustrated in FIG. 1, this section being taken substantially along 2-2 of FIG. 3;

FIG. 3 is a section taken substantially along 33 of FIG. 2 showing some portions of the structure as being broken away to expose to view other portions thereof;

FIG. 4 is a diagrammatic illustration of the structure of FIGS. 2 and 3 including the loaded spring mechanism provided for its operation which is omitted in FIGS. 2 :and 3; and

FIGS. 5 to 7 are diagrammatic illustrations of the same contact structure and linkage structure as shown in FIG. 4. in three different operating positions thereof.

Referring now to the drawings, and more particularly to FIG. 1 thereof, reference character T, has been applied to indicate a transformer winding having two taps a and a and reference characters R and R have been applied to indicate a pair of switching impedances formed by :a pair of ohmic resistors. The transfer switch comprises four pairs of movable contacts 27, 28, 29 and 30. Movable contacts 27 are adapted to engage fixed contacts 23, 23' and to part simultaneously from fixed contacts 23, 23. Movable contacts 28 cooperate in the same fashion with fixed contacts 24, 24'. The same applies in regard to movable contacts 29 and fixed contacts 25, 25' and in regard to movable contacts 30 and fixed contacts 26, 26. i

In the position shown in FIG. 1 contacts 27 are in engagement with contacts 23, 23 and contacts 29 are in engagement with contacts 25, 25'. Contacts 28 are out of engagement with contacts 24, 24' and contacts 30 are out of engagement with contacts 26, 26'. In the position of parts shown in FIG. 1 tap u of transformer winding T is conductively connected to the transfer switch terminal T by the following current path; tap n lead a, fixed contact 23, movable contacts 27, fixed contacts 23, lead b, terminal T.

If terminal T is to be disconnected from tap u and to be connected to tap a the following switching operations must be carried out sequentially in the specific sequence which is indicated below:

Contacts 27 part from contacts 23, 23, while contacts 29 remain in engagement with contacts 25, 25' and contacts 28 and 30 remain in the off positions thereof. Hence the following current path is being established: tap a lead 0, resistor R lead d, contact 25, contacts 29, contact 25', lead 11, terminal T. Y

The next step consists in engagement of contacts 38 and 26, 26', contacts 29 remaining in the closed position thereof and contacts 27 and 28 remaining in the open positions thereof. As a result the following current path is added to the aforementioned current path: tap a lead e, resistor R leaf 1, contact 26, contacts 30, contact 26, lead g, terminal T. As is apparent from the foregoing the turns of winding T situated between taps u and a are shunted by resistors R R in this position of the transfer switch, thus giving rise to circulating currents. The next operating step consists in separation of contacts 29 from contacts 25, 25, contacts 30 remaining in the closed position thereof and contacts 27 and 28 remaining in the open positions thereof. At this point of the tapchanging switching operation tap M1 is completely disconnected from terminal T and the shunt path for circulating currents including resistors R and R is interrupted.

The last step in the tap-changing switching operation of the transfer switch shown in FIG. 1 is closing of contacts 28, contacts 30 remaining in the closed position thereof and contacts 27 and 29 remaining in the open positions thereof. The last referred-to switching step establishes the following direct current path between tap u and terminal T: tap bi lead h, contact 24, contacts 28, contact 24, lead g, terminal T.

It appears from the foregoing that changing from tap u to tap a involves the following sequential steps:

(1) contacts 27 open; (2) contacts 30 close; (3) contacts 29 open; (4) contacts 28 close.

A certain interval of time occurs between each consecutive step, and the timing of these consecutive steps is referred to as the speed at which the tap-changing operation is performed.

Each pair of movable contacts 27, 28, 29, 30 has a velocity at which its parts and at which it engages its pair of cooperating fixed contacts 23, 23; 24, 24; 25, 25 and 26, 26'. This velocity is, of course, not constant along the travel or stroke of each pair of movable contacts 27, 28, 29, 30, but is zero in the two limit positions of contacts 27, 28, 29 and 30 and increases at the beginning of their travel or stroke and decreases at the end of their travel or stroke. The switching capacity or interrupting capacity of the breaks formed between separating contacts depends critically upon the rate of the dielectric recovery at each break, and the rate of dielectric recovery at each break depends, in turn, upon the time-travel characteristic of each pair of parting contacts. Hence it is of crucial importance to control the time travel characteristic of each pair of parting contacts irrespective of the timing of consecutive switching steps or, in other words, irrespective of the speed at which the tap-changing operation is being performed. The structures shown in the various figures are adapted to comply with this requirement.

As shown in FIG. 1 each pair of movable contacts 27, 28, 29, 30 is operated by a link 31. The ends of links 31 remote from the pairs of contacts 27, 28, 29, 30 are pivotally supported on a vertical floating shaft 33. Shaft 33 is under the action of a helical tension spring 36 whose radial- 1y outer end is attached to a pivot pin 38. Pivot pin 38 is 4 lever 40. The mechanism is designed to sequentially operate the four pairs of movable contacts 27, 28, 29, 30 in the manner set forth above. How this is achieved will be explained below more in detail in connection with FIGS. 4-7.

It'will be apparent from a consideration of FIG. 1 that cooperating pairs of fixed and movable contacts such as, for instance, contacts 23, 23 and 27, are provided to establish double breaks at each point of break. The structure shown in FIGS. 2 and 3 comprises also contacts forming double breaks at each point of break. The structure shown in FIGS. 4 to 7, inclusive, is a slightly simplified version of the structure shown in the other figures. It has been assumed in drawings FIGS. 4, to 7 that each pair of movable contacts 27, 28, 29, 38 of FIG. 1 is merged into one single contact and that each pair of fixed contacts is merged into one single contact, e.g., fixed contacts 23 and 23 are merged into one single contact. As a result, the double break feature of FIG. 1 is changed to single breaks, FIGS. 4 to 7, inclusive, showing the same contact structure as FIG. 1 upon having effected a contact merger as indicated above.

In FIGS. 4 to 7 four movable contacts 27, 28, 29, 30 take the place of the corresponding pairs of movable contacts shown in FIG. 1 and four fixed contacts 23, 24, 25, 26 take the place of the corresponding pairs of fixed contacts shown in FIG. 1.

Referring now more particularly to FIG. 4 numeral 1 has been applied to indicate a crank mechanism for loading a helical overcenter spring 9. Crank mechanism 1 may be operated either manually, or by appropriate motor means. The radially outer end of crank mechanism 1 is provided with a pin 2 engaging an elongated slot 3 in a spring-operating lever 4. Lever 4 is pivotally mounted at 6 and gear segment 5 is integral with lever 4. Gear segments 5 is in meshing engagement with a pinion 7 loosely mounted on a vertical shaft 10. Spring loading lever 8 is integral with pinion 7, thus transmitting any rotary motion of pinion 7 to the left end of spring 9. The right end of spring 9 is attached to a lever 11 keyed to shaft 10, or otherwise secured to shaft 10 in such a way as to always move jointly with shaft 10. The pivotal motions of lever 11 are limited by two abutments or dogs 12, 13, thus establishing two limit positions for lever 11.

Spring 9 is loaded'by operating crank mechanism 1. In the position of the constituent parts of the structure shown in FIG. 4 the operation 'of parts 1, 4, 5, 7 and 8 resulted in moving spring 9 over center, and spring 9 is about to pull lever 11 from its upper limit position defined by abutment 12 to its lower limit position defined by abut ment 13. The aforementioned lower limit position of lever 11 has been indicated by a dash-and-dot line to which reference character 11' has been applied. A pivotal motion of lever 11 under the action of spring 9 results in a corresponding pivotal motion of shaft 10, shaft 10 being integral with lever 11. A rotary motion of crank mechanism 1 of degrees results in a clockwise pivotal motion of lever 4 about fulcrum 6, and a clockwise rotary,

motion of pinion 7 and arm 8 from the position shown in solid lines in FIG. 4to the position indicated in FIG. 4 by a dash-and-dot line to which reference character 8 has been applied. Consequently spring 9 is again moved over center and lever 11 snaps from its lower limit position defined by abutment 13 to its upper limit position defined by abutment. 12.

Reference numeral 15 has been applied to indicate .the lower end or an extension of pivotable shaft 10.

The pivotal motions of the end or extension 15 of shaft 10 are transmitted by lever 48 to lever 40 pivotally supported at 42. Lever 48 and lever 40 are pivotally joined together by pin and slot means 46 allowing the point at which link 48 and lever 40 are pivotally connected to move relative to lever 40 in a direction longitudinally thereof. Helical tension spring 36 is interposed between the radially outer end 38 of lever 40 action mechanism shown in the upper portion of FIG.

4 is capable of pivoting the lower end or extension 15 of shaft 10 selectively in clockwise direction and in counterclockwise direction. Assuming now that the lower end or extension 15 of shaft 10 is being pivoted in clockwise direction; the time required for shaft 10 to turn a predetermined angle in clockwise direction depends upon the geometry of the over-center spring operating device shown on top of FIG. 4 and more particularly on the performance characteristics of its over-center spring 9. The pivotal motion of the lower end or extension 15 of shaft 10 is transmitted to lever 40 by the intermediary of lever 48. As a result, lever 40 is pivoted in clockwise direction about its fulcrum 42. The radially outer end 38 of lever 40 moves initially from its position 'along the center line between fixed contacts 23, 25

(FIGS. 4 and 5) to its position along the center line between fixed contacts 25, 26 (FIG. 6). This causes sequentially parting of movable contact 27 from fixed contact 23 and engagement of fixed contact 26 by movable contact 30. The speed at which contacts 23, 27 part and the speed at which contacts 26, 30 engage depends on the geometry of the contact operating structure shown in the lower portion of FIG. 4, and more particularly upon the performance characteristics of spring 36. The latter becomes operative to perform the aforementioned switching operations when the radially outer end 38 of spring 36 is being moved across the line connecting the center of floating shaft 33 and the center of fixed contact 25. As is apparent from FIG. 6 contacts 25, 29 remain closed and contacts 24, 28 remain open at the times contacts 23, 27 are opened and contacts 26, 30 are closed.

The clockwise pivotal motion of shaft 10 is not completed after completion of the aforementioned switching operations of contacts 23, 27 and 26, 30. As the lower end or extension of shaft 10 continues to movein clockwise direction, the radially outer end 38 of spring 36 is moved from the position shown in FIG. 6 to the position shown in FIG. 7. As a result, movable contact 29 separates from fixed contact 25 and movable contact 28 engages fixed contact 24, contacts 23, 27remaining separated and contacts 26, 30 remaining closed or engaged. Thus the changeover from one tap of a tapped transformer winding to another tap thereof such as, for instance, from tap u of FIG. 1 to tap u of FIG. 1 is completed.

The foregoing switching steps are reversed when shaft 6 each movable cont-act 27, 28, 29, 30 has a pair of contact surfaces cooperating with a pair of fixed contacts to establish double breaks upon parting from said pair of fixed contacts. In FIG. 2 but one of the four movable contact bridges is shown, but FIG. 3 clearly shows the four vertical contact bridges 27, 28, 29, 30. FIG. 3 shows only the upper fixed contacts 23, 24, 25, 26 cooperating with each contact bridge 27, 28, 29, 30. The lower fixed contacts 23, 24, 25, 26 indicated in FIG. 1 and present in the structure of FIGS. 2 and 3 do not appear in FIG. 3, and FIG. 2 shows only one of 15 is pivoted counterclockwise resulting in a movement of the parts of the transfer switch from the position shown in FIG. 7 to that shown in FIG. 5.

In the structure of FIGS. 2 and 3 eachfixed contact of the structure of FIGS. 47 has been replaced by a pair of fixed contacts arranged along a vertical line. Thus the fixed contact 23 of the structure of FIGS 4-7 has been replaced by the pair of contacts 23, 23', as

. diagrammatically shown in FIG. 1. Each movable conductively interconnect fixed contacts 23 and 23', and to part from fixed contacts 23, and 23'. The circuitry for the structure of FIGS. 2 and 3 is that of FIG. 1 wherein the four lower fixed contacts, i.e. contact 23'.

In FIGS. 2 and 3 numeral 21 has been applied to indicate a substantially cylindrical insulating structure forming a housing for the contact structure of the transfer switch and supporting the fixed contacts 23, 23; 24, 24; 25, 25' and 26, 26' forming part thereof.

As shown in FIG. 2, the driving shaft for operating the four movable cont-act bridges 27, 28, 29, 30 com prises two separate portions, i.e., an upper portion 10 and a lower portion or extension 15 axially spaced from the upper portion 10. Both portions 10, 15 are mechanically coupled for joint motion and electrically insulated from each other by an insulating sleeve 14.

A pair of axially spaced levers 48, 49 is fixedly mounted on shaft 15. It will be understood that lever 48 of FIGS. 2, 3 and 4 to 7, is substantially identical with lever 48 of FIG. 1, and that the structure of FIGS. 2 and 3 requires'the addition of another lever 49 performing the same function as lever 48. This is due to the fact that the substitution of vertical contact bridges 27, 28, 29, 30 for single break contacts 27, 28, 29, 30 arranged in a common plane calls for contact operat ing means of increased mechanical strength, coextensive with a significant portion of the length of shaft 15. These requirements are met in the structure of FIGS. 2 and 3 by duplication of many of the constituent elements of the structure of FIGS. 4-7. Thus levers 40 and 41 fulcrumed at 42 and 43, respectively, take the place of single lever 48 fulcrumed at 42, springs 36 and 37 take the place of single spring 36, and contact operating links 31 and 32 take the place of the single contact operating links 31 for each movable contact.

The radially outer ends of levers 48, 49 are provided formed in levers 40, 41. Pivots 38, 39 at the radially outer ends of levers 40, 41 form supports for the axially outer ends of springs 36 and 37, respectively. The axially inner ends of springs 36, 37 are attached to spring supports 34, 35 mounted respectively upon the upper end and upon the lower end of vertical floating shaft 33. Vertical floating shaft 33 pivotally supports the axially inner ends of pairs of contact operating links 31, 32 of which but the upper operating links 31 are shown in FIG. 3. The structure of FIGS. 2 and 3 comprises four pairs of contact operating links 31, 32. In FIG. 2 the axially inner ends of all contact operating links 31, 32 have been shown, but the axially outer ends of six of the contact operating links 31, 32 are broken away. Thus FIG. 2 shows fully but the pair of contact operating links for contact bridge 27 which are pivotally connected to the latter.

The structure of FIGS. 2 and 3 further comprises four transverse horizontal partitions 53, 54 and 44, 45 arranged inside of cylindrical insulating housing 2 1. Partitions 44 and 45 support or form a pair of bearings in which shaft 15 is journalled. Partitions 44 and 45 support also a pair of additional bearings forming fulcra for pivots 42 and 43 on levers 40 and 41. Partitions 53 and 54 form radial slots 51 and 52 for radially guiding the four contact bridges 27, 28, 29, 30.

The radially outer ends-of contact operating links 31, 32 pivotally support contact bridge supports which,

in turn, support the four contact bridges 27, 28, 29, 30. Layers 50 of insulating material are interposed between contact bridge supports 100 and contact bridges 27, 28, 29, 30, thus electrically insulating the latter from their operating means or linkages.

It will be understood that shaft 10 of the structure of FIGS. 2 and 3 is intended to be driven by a loaded spring mechanism such as that shown above in FIG. 4 and de scribed in connection therewith.

The mode of operation of the above described structure, i.e. that shown in FIGS. 2 and 3 is substantially the same as that described in connection with FIGS. 4 to 7, inelusive, except thatthe structure of FIGS. 2 and 3 establishes double breaks at each point where the structure of FIGS. 4 to 7, inclusive, establishes single breaks.

The term floating shaft is used in this context with reference to shaft 33 implies that the shaft is free to move in any direction under the action of a resulting force acting upon it, as distinguished from a shaft that is restrained from moving in any direction by suchmeans as, for instance, a groove, or the like guide means, limiting the free mobility of the shaft. Floating shaft 33 and the centers of movable contacts 27, 2'8, 29, 39, i.e., the points thereof where they are pivotally connected to links 3 1, determine four straight angularly displaced lines (see FIGS. 5 and 6). A snap action contact operation occurs any time the radially outer end of over-center spring 36 or pivot pin 38, respectively, is moved transversely across one of the above referred-to straight angularly displaced lines, or across one of the links 3d, respectively. It will be apparent from FIGS. 5 to 7 that the radially outer end of over-center spring 36 does not move transversely across all of the above-referred-to straight angularly displaced straight lines, or across all of links 31. The radially outer end of spring 36 or pin 38, respectively, is moved transversely across the links 31 pivotally supporting movable contacts 29 and 30, but not across the links 31 pivotally supporting movable contacts 23 and 28.

It will be understood that I have illustrated and de scribed herein a preferred embodiment of my invention and that various alterations may be made in the details thereof without departing from the spirit and scope of the invention as defined in the appended claims.

I claim as my. invention:

'1. A transfer switch for tapped regulating transformers comprising in combination:

(a) a plurality of fixed contacts arranged around a center in a circular pattern;

(b) a plurality of movable contacts each cooperating with one of said plurality of fixed contacts;

(c) a plurality of fixed radial guide means each for guiding one of said plurality of movable contacts radially into engagement with one of said plurality of fixed contacts and for guiding one of said plurality of movable contacts radially out of engage ment with one of said plurality of fixed contacts;

(d) a plurality of links each for operating one of said plurality of movable contacts, each supporting at one end and thereof one of said plurality of movable contacts, the ends of said plurality of links remote from said plurality of movable contacts and said plurality of fixed contacts defining a plurality of straight, angularly displaced lines;

(e) contact-operating means including an over-center (f) a floating shaft supporting the ends of said plurality of links remote from said plurality of movable contacts and further supporting one end of said overcenter spring, said floating shaft being free to move in any direction under the action of said over-center spring and not subject to any driving forces other than driving forces exerted by said over-center spring; and

10 comprising in combination:

(a) a plurality of fixed contacts arranged around a center in a circular pattern;

(b) a plurality of movable contacts each cooperating withone of said plurality of fixed contacts;

(c) a plurality of fixed radial guide means each for guiding one of said plurality of movable contacts radially into'engagement with one of said plurality of fixed contacts and for guiding one of said plurality of movable contacts radially out of engagement with one of said plurality of fixed contacts;

(d)v a plurality of links each for operating one of said plurality of'mova'ble contacts, each being pivotally connected at one end thereof to one of said plurality of movable contacts, the ends of said plurality of links remote from said plurality of movable contacts and the points of pivotal connection between 7 said plurality of movable contacts and said plurality of links defining a plurality of angularly displaced straight lines;

p (e) contact-operating means pivotally. connected to the ends of said pluralityof lin ks remote from said plurality of movable contacts for selectively moving each of said plurality of movable contacts radially inward and radially outward, said contact-operating means including a common floating support for said ends of said plurality of links remote from said plurality of movable contacts, lever means pivotally mounted in said center of said fixed contacts, and spring means interposed between said common floating support and the radially outer end of said lever means; and

(f) motor driven means for pivoting said radially outer end of said lever means in clockwise direction and in counterclockwise direction transversely across some of said plurality of straight angularly displaced lines to cause sequential snap-action-operation of said. plurality of movable contacts by said spring means.

3. A transfer switch for tapped regualting transformers comprising in combination: I

(a) a plurality of fixed contact means arranged around a center in a circular pattern;

(b) a plurality of cooperating movable contact means arranged inside of said circular pattern;

(0) an eccentric drive shaft for jointly operating said plurality of movable contact means;

(d) a source of motive power including a loaded spring for pivoting said drive shaft in clockwise direction and in counterclockwise direction between two limit positions thereof;

(e) a plurality of links each pivotally connected to one of said plurality of movable contact means; (f) a floating support pivotally supporting the ends of said plurality of links remote from said plurality of movable contact means;

(g) over-center spring means having one end supported by said floating support; and

(h) an over-center spring support supporting the other end of said spring means, said spring support being fulcrumed in said center of said circular pattern of fixed contact means and pivotally operated by said drive shaft along'a sufiiciently wide angle to effect snap-action operation of said plurality of movable contacts in a predetermined sequence.

4. A transfer switch for tapped regulating transformers comprising in combination:

(a) a plurality of fixed contact means arranged around a center in a circular pattern;

(b) a plurality of radially guided movable contact means each cooperating with one of said plurality of fixed contact means;

(c) first means substantially determining the speed of engagement and disengagement of said plurality of fixed contact means and of said plurality of movable contact means, said first means including a plurality of links each having one end pivotally connected to one of said plurality of movable contact means, a floating shaft pivotally supporting the ends of said plurality of links remote from said plurality of movable contact means, over-center spring means supported with one end thereof by said floating shaft, and a spring support for the other end of said overcenter spring means pivotally supported at said center of said circular pattern of fixed contact means; and 1 (d) additional means substantially determining the speed of sequential operation of said plurality of movable contact means including a drive shaft arranged parallel to said floating shaft, loaded spring means for pivoting said drive shaft in clockwise and counterclockwise direction between tWo limit positions thereof, and transmission means for transmitting the pivotal motion of said drive shaft to said spring support to pivot said spring support along an angle sufficiently wide to effect snap-action operation of a plurality of movable contacts in a predetermined sequence.

5. A transfer switch for tapped regulating transformers comprising in combination:

(a) a plurality of fixed contacts arranged around a center in a circular pattern;

(-b) a plurality of movable contacts each cooperating with one of said plurality of fixed contacts;

(c) a plurality of fixed radial guide means each for guiding one of said plurality of movable contacts radially into engagement with one of said plurality of fixed contacts and for guiding one of said plurality of movable contacts radially out of engagement with one of said plurality of fixed contacts;

(d) a plurality of linkages each for operating one of said plurality of movable contacts, each being pivotally connected at one end thereof to one of said plurality of movable contacts;

(e) contact-operating means pivotally connected to the ends of said plurality of linkages remote from said plurality of movable contacts for selectively mov ing each of said plurality of movable contacts radially inward and radially outward, said contact-operating means including a common floating shaft supporting the ends of said plurality of linkages remote from said plurality of movable contacts, lever means pivotally mounted in said center of said fixed contacts and tension spring means connecting said common floating shaft and the radially outer end of said lever means; and v (f) means for pivoting said lever means selectively in clockwise direction and in counterclockwise direction along an angle sutficiently wide to effect snap-action operation of said plurality of movable contacts in a predetermined sequence, said lever pivoting means including an over-center spring motor separate and spaced from said spring means.

6. A transfer switch for tapped regulating transformers comprising in combination:

(a) a substantially cylindrical contact support of insulating material;

(b) a plurality' of fixed contact means supported by said contact support in a circular pattern;

(c) a plurality of movable contact means cooperating with said plurality of fixed contact means;

(d) transverse partition means inside, of said contact support having radial slots defining ways for guiding said plurality of movable contact means;

(e) a plurality of linkages each for operating one of said movable contact means each being pivotally connected at one end thereof to one of said plurality of movable contact means;

(f) a common floating shaft supporting the ends of said plurality of linkages remote from said plurality of movable contact means;

(g) lever means pivotally mounted in coaxial relation to the longitudinal axis of said contact support; (h) tension over-center spring means interconnecting said common floating shaft and said lever means; (i) operating means for pivoting said lever means selectively in clockwise direction and in counterclockwise direction, along a sufliciently wide angle to effect sequential snap-action operation of said plurality of movable contact-s; and

(j) a spring motor separate and spaced from said over-center spring means for operating said operatmg means. 1

7. A transfer switch for tapped regulating transformers comprising in combination:

(a) a substantially cylindrical contact support of insulating material; (b) a plurality of fixed contact means supported by said contact support in a circular pattern;

(0) a plurality of movable contact means cooperating with said plurality of fixed contact means;

(d) transverse partition means inside of said contact support having radial slot-s defining ways for guiding said plurality of movable contact means;

(e) a plurality of linkages each for operating one of said plurality of movable contact means each being pivotally connected atone end thereof to one of said plurality of movable contact means;

(f) a common floating shaft supporting the ends of said plurality of linkages remote from said plurality of contact means;

(g) lever means pivotally mounted in coaxial relation to the longitudinal axis of said contact support; (h) over-center tension spring means interconnecting said floating shaft and said lever means;

(i) operating means for pivoting said lever means se lectively in clockwise direction and in counterclockwise direction along a sufficiently wide angle to effect sequential snap-action operation of said plurality of movable contacts; and

(j) an additional over-center spring means spaced and separate from said over-center tension spring means for operating said operating means.

8; A transfer switch for tapped regulating transformers comprising in combination:

(a) a substantially cylindrical contact support of insulating material;

(b) a plurality of fixed contact means supported by said contact support in a circular pattern;

(c) a plurality of movable contact means cooperating with said plurality of fixed contact means;

((1) transverse partition means inside of said contact support having radial slots defining ways for guiding said plurality of movable contact means;

(e) a plurality of linkages each for operating one of said plurality of movable contact means each being pivotally connected at one end thereof to one of said plurality of movable contact means;

(f) a common floating shaft supporting the ends of said plurality of linkages remote from said plurality of movable contact means;

(g) a first lever means pivotally mounted in coaxial relation to the longitudinal axis of said contact support and having an oblong recess; (h) over-center tension spring means interconnecting said common floating shaft and said first lever means;

(i) a second lever means fixedly mounted on a second shaft parallel to said common floating shaft and spaced from said longitudinal axis of said contact support, said second lever means having a pin engaging said oblong recess in said first lever means; and

(j) a snap-action spring motor adapted to pivot said sec- :ond shaft in clockwise direction and in counterclockwise direction to cause sequential snap-action operation of said plurality of movable contacts by the intermediary of said over-center tension spring means.

9. A transfer switch for tapped regulating transformers comprising in combination: 7

(a) a contact support of insulating material;

(b) a plurality of upper fixed contacts supported by said contact support and circularly arranged around a first center;

(c) a plurality of lower fixed contacts supported by said contact support and arranged circularly around a second center;

(d) a plurality of vertical contact bridges each cooperating with one of said plurality of upper fixed contacts and one of said plurality of lower fixed contacts; a

(e) a pair of horizontal partitions arranged inside of said contact support;

(f) a driving shaft resting in a pair of bearings each supported by one of said pair of partitions;

(g) a first contact operating spring having performance characteristics substantially determining the speed of the sequence of operation of said plurality of Contact bridges, said first contact operating spring being arranged adjacent one end of said driving shaft and adapted to pivot said driving shaft in clockwise direction and in counterclockwise direction between two limit positions thereof;

(h) a plurality of pairs of links, each pair of links having ends pivotally connected to one of said plurality of contact bridges;

(i) a floating shaft arranged in the space bounded by said pair'ofpartitions pivotally supporting the ends of said plurality of pairs of links remote from said plurality of contact bridges;

(j) a pair of levers pivotable about an axis defined by the line interconnecting said first center and said second center of said plurality of upper contacts and said plurality of lower contacts, each of said pair of levers having a fulcrum supported by one of said pair of partitions;

(k) a pair of transmission means interconnecting said driving shaft and said pair of levers to transmit the V pivotal motions of said driving shaft to said pair 7 of levers; and (1) additional contact-operating means having performance characteristics substantially determining the speed of the radial opening and the speed of the radial closing motion of said contact bridges, said additional contact-operating means including a pair of helical tension springs each having one end attached to one of said pair of levers and each having another end attached to one of the ends of said floating shaft. 10. A transfer switch for tapped regulating transformers comprising in combination:

, (a) a substantially cylindrical contact support of insulating material;

(b) a plurality of upper fixed contacts arranged at the same level and supported by said contact support; a plurality of lower fixed contacts arranged at the same level and supported by said contact support; (d) a plurality of radially movable contact bridges arranged inside said contact support each cooperating with one of said plurality of upper fixed cont-acts and one of said plurality of lower fixed contacts;

(e) a pair of axially outer transverse partitions fixedly arranged inside said contact support;

(f) a vertical driving shaft arranged eccentrically inside said contact support and supported by said pair of axially outer partitions;

(g) a pair of axially inner partitions fixedly arranged inside said contact support and having a plurality of radial slots each engaging with radial edges thereof one of said plurality of contact bridges and each providing a radial guide means for one of said pluralityof contact bridges;

(h) a plurality of pairs of links, each of said plurality of pairs having ends pivotally connected to one of said plurality of contact bridges;

(i) a floating shaft arranged inside the space bounded by said pair of axially outer partitions pivotally supporting the other ends of each of said plurality of pairs of links;

(j) a pair of levers pivotable about the longitudinal axis of said contact support each having afulcrum supported by one of said pair of axially outer partitions;

' (k) a pair of transmission linkages interconnecting said driving shaft and said pair of levers to transmit pivotal motions of said driving shaft to said pair of levers; and

(l) a pair of helical tension springs each having one end attached to one of said pair of levers and another end attached to one of the ends of said floating shaft.

11. A transfer switch for tapped regulating transformer comprising in combination.

(a) a plurality of fixed contacts circularly arranged around a center;

(b) a plurality of movable contacts guided along radii of a circle defined by the arrangement of said plurality of fixed contacts, each of said plurality of movable contacts being adapted to engage one of said plurality of fixed contacts and to be disengaged from one of said plurality of fixed contacts;

(c) a driving shaft arranged at right angles to the plane defined by said plurality of fixed contacts in spaced relation from said center of said circle;

((1) a first lever integral with said driving shaft havirig a pin adjacent the end thereof remote from said driving shaft;

(e) a second lever fulcrumed at said center of said circle and defining an oblong slot engaged by said of links remote from said plurality of movable cont acts; and g (h) a tension spring having one end attached to said second lever at a point thereof more remote from said center than said oblong slot, said tension spring having another end attached to said floating shaft.

' 12. A transfer switch for tapped regulating transform ers comprising in combination:

(a) a plurality of fixed contacts circularly arranged around a center;

(b) a plurality of movable radially guided contacts each cooperating with one of said plurality of fixed contacts;

(c) a driving shaft arranged at right angles to the plane defined by said plurality of fixed contacts and spaced from said center;

(d) a contact-operating mechanism arranged adjacent the upper end of said driving shaft and including loaded spring means for pivoting said shaft in clockwise direction and counterclockwise direction between two limit positions thereof;

(e) a first lever integral with said driving shaft arranged 7 adjacent the lower end thereof, said first lever having pin means adjacent the end thereof remote from said driving shaft;

(f) a second lever fulcrumed at said center of said plurality of fixed contacts and having means cooperatively engaging said pin means and allowing said pin means to move relative to said second lever in a direction longitudinally thereof;

(g) a plurality of links each having one end pivotally secured to one of said plurality of movable contacts;

(h) a floating shaft arranged parallel to said first shaft pivotally supporting the ends of said plurality of links remote from said plurality of movable contacts; and

(i) a tension spring having one end attached to said second lever and another end attached to said floating shaft.

13. A transfer switch for tapped regulating transformers comprising in combination:

(a) a plurality offixed upper contacts circularly arranged around a center;

(b) a plurality of fixed lower contacts each arranged in registry with one of said plurality of fixed upper contacts;

(c) a plurality of movable radially guided contact bridges each cooperating with one of said plurality of fixed upper contacts and one of said plurality of fixed lower contacts;

(d) a driving shaft arranged at right angles to the plane defined by said plurality of fixed upper contacts and at right angles to the plane defined by said plurality of fixed lower contacts and in spaced relation from said center of said plurality of fixed upper contacts and said center of said plurality of fixed lower contacts;

(e) loaded spring means for pivoting said driving shaft in clockwise direction and counterclockwise direction between two limit position thereof;

(f) a first pair of levers jointly movable with said driving shaft and projecting at right angles therefrom, each of said first pair of levers having a pin adjacent the end thereof remote from said driving shaft extending parallel to said driving shaft;

(g) a second pair of levers fulcrumed to pivot about an axis extending through said center of said upper plurality of fixed contacts parallel to said driving shaft, each of said second pair of levers having a longitudinal slot engaged by said pin on one of said first pair of levers;

(h) a plurality of pairs of links each having ends pivotally secured to one of said plurality of contact bridges;

(i) a floating shaft arranged parallel to said driving shaft in spaced relation from said pivot axis of said second pair of levers pivotally supporting the ends of said plurality of pairs of links remote from said plurality of contact bridges; and

(j) a pair of tension springs each having one end attached to one of said second pair of levers and another end attached to spaced points of said floating shaft.

References Cited by the Examiner UNITED STATES PATENTS 10/1939 Hill 200-66 X 5/1958 Jansen. 

1. A TRANFER SWITCH FOR TAPPED REGULATING TRANSFORMERS COMPRISING IN COMBINATION: (A) A PLURALITY OF FIXED CONTACT ARRANGED AROUND A CENTER IN A CIRCULAR PATTERN; (B) A PLURALITY OF MOVABLE CONTACTS EACH COOPERATING WITH ONE OF SAID PLURALITY OF FIXED CONTACTS; (C) A PLURALITY OF FIXED RADIAL GUIDE MEANS EACH FOR GUIDING ONE OF SAID PLURALITY OF MOVABLE CONTACTS RADIALLY INTO ENGAGEMENT WITH ONE OF SAID PLURALITY OF FIXED CONTACT AND FOR GUIDING ONE OF SAID PLURALITY OF MOVABLE CONTACTS RADIALLY OUT OF ENGAGEMENT WITH ONE OF SAID PLURALITY OF FIXED CONTACTS; (D) A PLURALITY OF LINKS EACH FOR OPERATING ONE OF SAID PLURALITY OF MOVABLE CONTACTS, EACH SUPPORTING AT ONE END AND THEREOF ONE OF SAID PLURALITY OF MOVABLE CONTACTS, THE ENDS OF SAID PLURALITY OF LINKS REMOTE FROM SAID PLURALITY OF MOVABLE CONTACTS AND SAID PLURALITY OF FIXED CONTACTS DEFINING A PLURALITY OF STRAIGHT, ANGULARLY DISPLACED LINES; (E) CONTACT-OPERATING MEANS INCLUDING AN OVER-CENTER SPRING; (F) A FLOATING SHAFT SUPPORTING THE ENDS OF SAID PLURALITY OF LINKS REMOTE FROM SAID PLURALITY OF MOVABLE CONTACTS AND FURTHER SUPPORTING ONE END OF SAID OVERCENTER SPRING, SAID FLOATING SHAFT BEING FREE TO MOVE IN ANY DIRECTION UNDER THE ACTION OF SAID OVER-CENTER SPRING AND NOT SUBJECT TO ANY DRIVING FORCES OTHER THAN DRIVING FORCES EXERTED BY SAID OVER-CENTER SPRING; AND (G) CONTACT-OPERATING MEANS INCLUDING A SOURCE OF MOTIVE POWER FOR SELECTIVELY MOVING THE OTHER END OF SAID OVER-CENTER SPRING IN A CLOCKWISE AND IN A COUNTERCLOCKWISE DIRECTION ABOUT SAID CENTER OF SAID PLURALITY OF FIXED CONTACTS SEQUENTIALLY ACROSS SOME OF SAID STRAIGHT ANGULARLY DISPLACED LINES TO CAUSE SNAP ACTION OPERATION OF SAID PLURALITY OF MOVABLE CONTACTS. 